1. Field of the Invention
The present invention relates to a device for muting a ringer of a telephone, more particularly, a device placed in series with a telephone ringer and having a gate alterable between a non-conductive state and a conductive state whereby a ring signal is selectively passed to the ringer. A remote calling party may activate the conductive state of the gate by sending a first and last ring signal separated by a preselected time interval and dependent upon the selected mode of the device at the terminal telephone.
2. Description of the Prior Art
The present invention primarily addresses a problem that many people who work at night and sleep during others' waking hours face, namely, daytime telephone calls. Each telephone call sets off a ringer which can disturb the sleeping called party. Yet, if the called party simply shuts off the telephone ringer, the called party isolates himself or herself from desired telephone calls.
Various solutions to screen disturbing or undesirable incoming phone calls and mute the ring-tone can be found in the prior art. Each of these solutions rely on recognition by the screening device of a code which must be known to the calling party. Often, in order to ring the telephone, the calling party must enter a specific code which activates the receiving telephone ringer. However, the systems used to recognize the code differ from one to another.
For example, a system based in dual tone multi-frequency recognition (DTMF or touch tones) is provided by U.S. Pat. No. 5,157,712 issued Oct. 20, 1992 to Wallen, Jr. It describes a device which instructs a calling party to manually enter a touch-tone code after a first tone is produced. If the code is properly provided, the terminal telephone rings; otherwise, only a message is taken. The use of a touch-tone recognition device to activate a ringer is inapplicable to the present invention.
U.S. Pat. No. 4,937,854 issued Jun. 6, 1990 to Sarakas describes a call screening device to avoid unwanted phone calls wherein the calling party must also use DTMF signals to enter a requested security code to activate and deactivate the device remotely. The '854 patent also teaches away from the present invention because the device is intended for use on a network of telephones, wherein, when the correct security code is entered, the device activates a ringing circuit to all telephones on the network.
U.S. Pat. No. 4,891,834 issued Jan. 2, 1990 to Sezaki et al. describes a telephone capable of being switched between its ordinary function and a "message function" for recording confidential messages by using the proper code. The telephone uses a ring signal identification circuit in series between the incoming ring signal and a terminal telephone and counts a predetermined number of ring signals without ringing the terminal telephone's ringer. If a calling party privy to the proper code once disconnects the call and originates a second call within a predetermined time interval timed by a counter within the device, the device requests an identifying multi-frequency signal password, and thereupon changes the condition of the telephone from its ordinary to message function. The timing logic circuit used in the counter counts the number of ring pulses; i.e., the subsequent timing operation of the '834 device necessarily depends upon the timing logic circuit to count the number of ring signal pulses by sensing the number of continuous 16 Hz 1/2 second signals received before sending any signal to the telephone or ringer. Moreover, the calling party controls the message function and not the ringer, which function can be accessed only by a calling or receiving party with the proper DTMF code.
Japanese publication No. 1-255348 published Oct. 12, 1989 by Inoue describes a telephone call screening device which prevents a ringer from being sounded. When a call is received by the device, a count-up is executed by a counter, which then compares the frequency of rings (i.e. number of rings) to a preset frequency figure.
Japanese publication No. 1-177246 published Jul. 13, 1989 by Nakagawa describes a telephone system having caller-selected functions which allow the calling party to reach a receiving telephone without knowing a code number. A translated abstract of the publication describes a switch circuit which produces a "fixed time action condition when calling signals dissipate after the prescribed number of calling signals arrive". Subsequently, if a second call signal is received while the "fixed time action condition" is active, a second action condition is produced by a "first calling signal generating circuit". An audible sound is then generated by these circuits. The logic appears to significantly differ from the present invention.
Other means to silence telephone ringers are also known; however, these fail to allow a calling party to activate the device. For example, U.S. Pat. No. 5,317,632 issued May 31, 1994 to Ellison describes a simple timer for selectively disabling a telephone ringer for a selected time period. The called party simply turns a mechanical selector knob to set a quartz clock which counts down, during which time the telephone ringer is silent. U.S. Pat. No. 5,351,289 issued Sep. 27, 1994 to Logsdon et al. describes a "caller ID" circuit logic to automatically block calls originating from particular telephone numbers. The system is also not capable of being remotely activated to allow passage of a ring signal. European Patent Application No. 0 559 047 by Inglehart published Sep. 8, 1993 also describes an apparatus that blocks a telephone ringer when receiving calls from a designated telephone number.
U.S. Pat. No. 5,191,607 issued Mar. 2, 1993 to Meyers et al. describes a ring-tone muting device controlled by an operator in high-stress communications operations when the operator has the need to eliminate background noise. A timer prevents indefinite or permanent muting by automatically disabling a ring-tone mute circuit after a programmable period of time has passed from when the operator manually muted the ring-tone. A visual reminder is provided while the ringing is muted.
U.S. Pat. No. 4,065,642 issued Dec. 27, 1977 to McClure describes an answering/messaging system for automatically sensing and signaling the presence of a message, by means of automatic and repetitive dial and paging features. The device includes a timing feature which merely discontinues dialing if a remotely dialed location does not answer.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.